This invention relates to a machine for locating an operator with respect to an object, and more particularly to a versatile machine tool in which the tool can be moved in three lineal directions and three rotational directions in relation to the surface of a workpiece.
The most versatile form of cutting tool type machine tool presently in use is the so-called machining center which typically can accomplish milling, drilling, boring and tapping operations in up to five axes of movement, the three linear orthagonal axes and two rotational directions. Since its introduction over thirty years ago, the machining center's basic components have not changed. They typically include a bed, an upright column and a spindle head carried by the column. A rotary table for holding a workpiece is typically mounted on the bed and provides one of the rotary directions of motion. The column and table move relative to each other for one of the linear directions of motion, the spindle head and table move relative to each other in a vertical direction for a second linear axis of motion, and the spindle head and workpiece move horizontally with respect to each other for the third linear direction of motion. The fifth axis is provided by rotating the spindle head or the work table in a vertical plane relative to each other.
A sixth axis of rotary motion is available in the present machining centers by controlling the angular position of the spindle. The present machining centers may have either a horizontal spindle or a vertical spindle and they typically are controlled by computer numerical control. The machining centers usually have mechanisms for automatically changing tools from and to a magazine of tools associated with the machining center, and will often have automatic workpiece handling as well.
To achieve the full six axes of motions in a present machining center requires that the movements of the table, column, spindle head, spindle, and bed be coordinated and that these sometimes massive components be moved in very controllable finite increments. Because all of these components are being moved, many times simultaneously under computer numerical control, accuracy requires a rigidity to the components and an accurate path through which the components can be moved. This has resulted in the development of more rigid and massive components such as for the bed and column and very expensive and finely formed ways along which the components can travel relative to each other in the linear directions.
Although the modern machining center provides very accurate machining, the machining center becomes very complex and expensive when it is designed to provide the maximum versatility of being able to machine any point on the exposed five surfaces of the typical cubic workpiece.